Patented Infinite Shape Feature (ISF) in Blackstar amps

[exclamationmark]

Well, that patent, if granted, dies a violent death the very second anybody, not even you, refers to your Geofex article.

I don't think this is necessarily true, unless the patent office actually has an obligation to chase up any claims (for free...). Usually court battles are fought over this sort of stuff. In order for something to be patentable it must show an 'inventive step' (whatever the patent office decides this to be) and not be common public knowledge. There have been an ENORMOUS amount of cases fought based on the latter assumption. For instance a rather large pharmaceutical company actually lost the rights to patent their product in Australia because they had patented their product in other countries before doing this in Oz, thus deeming their invention common public knowledge. From there, it was basically free reign for any company in Australia to produce this drug. Note that this case was actually instigated by one their competitors and the patent wasn't simply transferred to anyone; it was actually abolished.

[J M Fahey]

Dear exclamation mark.
Maybe I was not clear.
I meant the patent dies, not at the Patent office, but functionally, as something that protects you from competition.
Problem is, infringers usually donīt care to prove anything, they just copy you and pocket the cash.
*If* you start legal procedures, which considering the expenses and headaches remains a big *if*, only then the accused (which may be only one among many) will have to defend himself, which he can do by referring to an earlier publication ..... or even ignoring you and letting you start and move the case forward.
The famous litigation cases we all read about, are among Industry giants (Microsoft/Apple/Samsung/Sony/HP/Google) which are fighting for zillions of dollars and have the Lawyer armies (and Political connections) necessary .... but at a smaller scale often itīs out of reach.
Imagine some Chinese OEM company copies the ISP .... Blackstar may sue them, no doubt, Iīm sure it will be a big headache.
well, itīs just a personal opinion

[Steve Conner]

That document isn't a patent, it's a rejected patent application. Look at the last page.

Bruce Keir of Blackstar (formerly of Marshall) has one patent which can be seen here:
Patent US5467400 - Solid state audio amplifier ... - Google Patents

I believe it is for the thing that Marshall used before Valvestate: FDD or whatever.

Usually when a small company says "patented" they mean "patent pending". I'm named as an inventor on three or four patent applications, but none of them has ever been granted. Here's one that expired.
Patent US20040136055 - Automatic power control of a ... - Google Patents

[J M Fahey]

I'm named as an inventor on three or four patent applications

WOW !!!!!
And Iīm not kidding

[tedmich]

That document isn't a patent, it's a rejected patent application. Look at the last page.

Bruce Keir of Blackstar (formerly of Marshall) has one patent which can be seen here:
Patent US5467400 - Solid state audio amplifier ... - Google Patents

I believe it is for the thing that Marshall used before Valvestate: FDD or whatever.

Usually when a small company says "patented" they mean "patent pending". I'm named as an inventor on three or four patent applications, but none of them has ever been granted. Here's one that expired.
Patent US20040136055 - Automatic power control of a ... - Google Patents

PAF!! indeed

[Steve A.]

I did find that there was a patent issued on the idea of using a variable voltage, variable resistance output on a voltage regulator to fake a dying battery for pedals. It's not mine.

It was applied for six months after I published the scheme at geofex.

I saw the Dan Electrode DA-4 power supply recently with an adjustable voltage from 3 to 9 vdc... AND it can power up to 15 pedals! Does anybody actually have 15 pedals that sound better at one specific reduced voltage? For a lot of pedals you want the headroom from the full voltage (in fact some of them sound even better with 12vdc, 16vdc or 18vdc). It would make a LOT more sense to me if the DA-4 could supply both the full voltage and a variable voltage at the same time. If you are going to run multiple pedals you are going to need a daisy chain cord so you could plug that into a jack on the wall wart which supplies the full 9vdc. While the cord permanently attached to the wall wart would be the variable supply (set it to 9vdc if you want the full voltage.)

Dan Electrode

There was some griping around here when we found out that Sal Trentino had patented the fixed bias/cathode bias switch in the mid-90's as I recall. 6 months before the date of the patent application Dan Torres had included a design for a fixed bias/cathode bias switch in his column for Vintage Guitar magazine. It wasn't his design- someone in Europe had come up with it and mailed him the drawing. What was really cool was that it used just a single pole double-throw switch (most designs would use a DPDT switch). This was specifically for a Fender blackface amp and it did involve replacing one of the resistors in the bias supply circuit.

I had included a fixed bias/cathode bias switch in my mods for the Pignose G40V so I sent an email to Sal to see if he wanted me to redact it from my article. But he was cool about presenting the switch in a non-profit educational context. It was the amp mfgs who would have to pay him royalties if they were to include it in their amp. (Some of the mfgs got around that by using a fixed bias/cathode bias switch, but calling it something else altogether.)

I think that patents are great because disseminate ideas rather than hide them under a bushel. We can study the designs- or at least a rough sketch of them.

Steve Ahola

[Steve A.]

That document isn't a patent, it's a rejected patent application. Look at the last page.

Are you referring to the 14 page ISF patent application PDF posted at sewatt.com? I just looked at the last page again and did not see anything that looked like a rejection notice.

I think that a lot of amp mfgs will submit patent applications with the hope that it might impress potential customers. "These guys aren't just copying everybody else's design- they have come up with something new that can be patented. I need to check that out!"

With guitars and amps it seems like copyrighted trademarks are enforced more than patents. Like guitar headstocks and body shapes. And possibly the Dumble Overdrive Special logo (it seems like the cloners are afraid to copy his logo although they have no problems copying his designs.)

Steve Ahola

[J M Fahey]

Yes, Trademarks and Logos are *very* easy to enforce.
Remember you have to convince a Judge, who is versed in other knowledge but not a Technical one , that you are right.
*Anybody* will notice that your "Dumble" trademark is the same as the "Dumble" Howard patented in, say, 1 microsecond.
And realizing that your brown sweet carbonated water called "Koka Kola" might hurt Coca Cola would take less than a minute.
But if , say, the classic TMB Fender tone control were patented, and the infringer had one with doubled Cap values and halved R and Pot values (which ends having the exact same EQ curves) it would be very difficult to defend in Court.
The infringerīs Lawyer might easily say: "Your Honor, *no* part value in the Defendantīs schematic matches the Patented one" ..... and he would be right.
I remember the first Tube patent was challenged in Court and almost overturned because the tube was explained to the Judge as "some kind of lamp" and the Judge saw with his own eyes that "it was a very poor kind of Lamp, that it provided very little light"
I have 1 Patent registered in Argentina and Spain and two Trademarks registered in my name, and my Patent Lawyer always insisted: "provide as little and as generic detail as possible in the Application, or it will be very easy to beat by a minor variation"

As of the patent linked earlier, I see two contradicting statements at the end :
1) it says "valid from 01/01/2006) on" which looks like it was granted after all , and
2) the first three "claims" which define what is *really* being patented are crossed with an "X" , "because they exist on earlier patents" , more specifically they say that there exists a "document indicating lack of novelty or inventive step" which is ground for denying.
All other earlier patents mentioned are labelled "A", which maybe does not hurt.
Or maybe I understood it upside down.
Really not sure, Iīm not a Lawyer.
Maybe Steve Conner knows better by being in closer contact with this stuff than us.

[Steve A.]

But if , say, the classic TMB Fender tone control were patented, and the infringer had one with doubled Cap values and halved R and Pot values (which ends having the exact same EQ curves)

I agree that they should have the same EQ curve but I was wondering if anybody has tried doing an A/B test with those two tone stacks.

Steve

[diagrammatiks]

probably wouldn't be too much different except in the way that the EQ interacted since you'd need different pot values.

looking over some of the schematics I have...it seems like you'd generally need a .1 and a .2 400v rated cap. those get pretty big...


actually looking over it some more I'm not sure if that would technically be possible or as easy as simply halving and doubling...

the initial filter values are selected in relation to the output impedance of the triode stage.

[J M Fahey]

I agree that they should have the same EQ curve but I was wondering if anybody has tried doing an A/B test with those two tone stacks.

It was just an example on the not-so-perfect patent protection provided to many electronics circuits.
Donīt read too much into it.
Thatīs why. AFAIK, actual schematics are not patented, while, curiously, their *drawing* may be protected (as work of art).
As of the results, a same-curves halved impedance wonīt work the same if driven from a triode plate (as in BF/SF Fenders) with its relatively high intrinsic impedance, but I *guess* (didnīt do the Math, may be wrong) that when driven by a cathode follower the difference may be barely audible, if any.
When driven by an Op Amp, the difference is inexistent for all practical ends.

[Chuck H]

It's all about who actually knows what's going on. "WE" here at AMPAGE (or MEF, whatever) know and exploit all manor of circuit manipulation and see Randall Smith's patents and this BlackStar patent as pedantic. But we are an obsessive bunch. We know that in an overdriven guitar amplifier the slope resistor can make or break the overall tone. To a patent court, that AT BEST has the consultation of some lab coat EE, the slope resistor is a pedestrian issue based purely in the final balance and knee frequencies. Add the caveate that the amp is intended to be overdriven, so all inclusive chaos must be considered, and any consulting EE will throw up their hands. Forced to admit that the refinement of overdrive is a black art that is opposed to any schooling or known technologies. At this point the decision must be made based on the FACT that no one in the loop besides the claimant has a real clue about what's going on... Pattent granted. Even if some minority (like us) knows it's old news, we don't happen to be in on the arbitration. That's how these patents get granted. The only thing anyone wanting to use patented technology, as it applies to guitar amps, has is the likelyhood that they can demonstrate a precident. Which has become eminently more possible with information technologies.

JM2C

[diagrammatiks]

i think the bigger issue is that people in the know and who aren't trying to make money off their ad copies realize that the type of circuit given in the isf is pretty much worthless.

[J M Fahey]

I think being able to change the tone controls frequency turnover points has some practical utility.
The example graphs show it can go from about 250Hz (classic Fender) to 750Hz (beyond Ampeg.
A 3:1 frequency change is *very* noticeable.

Too tired to draw now, but Iīll post two variable turnover tone controls I used successfully in many amplifiers; one of them with a 3PDT switch changing treble control frequencies 5:1 (*very* noticeable) and another one with a midrange slope pot.

[diagrammatiks]

right but it's all about how that ends up working within the rest of the circuit.

The graph does show a noticeable shift but the turnovers are also interacting with the rest of the tone controls.